I am experiencing the same issue. Below is a minimal reproducible sample. It works on iOS 26 and 26.1 but fails on iOS 26.2. @Test func testSimulatedErrorForLoadProducts() async throws { try await skSession.setSimulatedError(.generic(.unknown), forAPI: .loadProducts) let failure = await skSession.simulatedError(forAPI: .loadProducts) #expect(failure != nil) // ✅ await #expect(throws: Error.self) { // ❌ Expectation failed: an error was expected but none was thrown _ = try await Product.products(for: ["product_id"]) } }